Page. Rank in Map. Reduce n 1 [n 2, n 4] n 2 [n 3, n 5] n 2 n 3 [n 4] n 4 [n 5] n 4 n 5 [n 1, n 2, n 3] Map n 1 n 4 n 2 n 5 n 3 n 4 n 1 n 2 n 5 Reduce n 1 [n 2, n 4] n 2 [n 3, n 5] n 3 [n 4] n 4 [n 5] n 5 [n 1, n 2, n 3] n 3 n 5
Phase 2:Page. Rank. Iter伪代码
Phase 3:Rankviewer Page. Rank. Viewer:将最终结果排序输出。 • Page. Rank. Viewer从最后一次迭代的结果读出文件,并将文件名 和其PR值读出,并以PR值为key网页名为value,并且以PR值从 大到小的顺序输出。 • 排序过程中可以采用框架自身的排序处理,重载key的比较 函数,使其经过shuffle和sort后反序(从大到小)输出 public static class Dec. Float. Writable extends Float. Writable { … @Override public int compare. To(Object o) { return -super. compare. To(o); } }
Dijkstra最短路径算法 1 10 2 0 3 9 6 7 5 2 Example from CLR 4
Dijkstra最短路径算法 1 10 10 2 0 3 9 6 7 5 5 2 Example from CLR 4
Dijkstra最短路径算法 1 8 14 10 2 0 3 9 6 7 5 5 7 2 Example from CLR 4
Dijkstra最短路径算法 1 8 13 10 2 0 3 9 6 7 5 5 7 2 Example from CLR 4
Dijkstra最短路径算法 11 8 9 10 2 0 3 9 6 7 5 5 7 2 Example from CLR 4
Dijkstra最短路径算法 1 8 9 10 2 0 3 9 6 7 5 5 7 2 Example from CLR 4
Reference 1. The Anatomy of a Large-Scale Hypertextual Web Search Engine. Sergey Brin and Lawrence Page. 2. Ecient Computation of Page. Rank. Taher H. Haveliwala. 3. The Page. Rank Citation Ranking: Bring Order to the Web 4. Data-Intensive Text Processing with Map. Reduce Jimmy Lin and Chris Dyer